1. Field of the Invention
This invention relates to a method for processing a taste-modifier. More particularly, it relates to a method for processing a taste-modifier comprising fresh curculigo latifolia fruits, dried fruits thereof or a curuculin-containing material obtained therefrom into a stable form suitable for effectively exhibiting the taste-modification effect of the same.
2. Description of the Prior Art
Known taste-modifiers, which affect the receptor membranes on the tongue in such a manner as to modify the taste of a food, include those which remove the sweetness of a sweet food in the mouth, for example, gymnemic acid contained in Gymnema sylvestre leaves and ziziphine contained in Ziziphus jujuba leaves; and those which convert the sourness of a sour food into sweetness in the mouth, for example, miraculin contained in Synsepulm dulcificum fruits.
It is further known that Curculigo latifolia fruits, which grow in Western Malaysia and the southern part of Thailand and belong to the genus Curculigo of Amaryllidaceae, are good to eat and exhibit an appetizing effect.
Although miraculin has the abovementioned effect, it is not put into practical use as a taste-modifier because of its poor stability.
No effect of Curculigo latifolia fruits except the abovementioned one has been known so far.
The present inventors have found that a sour material or water taken after eating Curculigo latifolia fruits would taste sweet. Thus they have attempted to identify the sweetness-inducer. As a result, they have found that a specific protein contained in Curculigo latifolia fruits is the aimed sweetness-inducer (cf. Japanese Patent Application No. 153143/1988). This protein is named curuculin. In order to utilize this curuculin as a taste-modifier on a commercial scale, it is required to obtain said taste-modifier by as a simple method as possible. It is further required to process said taste-modifier into a stable form suitable for effectively exhibiting the taste-modification effect.
Pure curuculin may be obtained by washing fresh Curculigo latifolia fruits or dried fruits thereof with water, extracting them with an aqueous solution of a salt and purifying the extract by ion-exchange chromatography with the use of CM-Sepharose and HPLC with the use of a gel column. Pure or almost pure curuculin would remain stable for a month or longer in the form of an aqueous solution at room temperature. However fresh Curculigo latifolia fruits, dried fruits thereof or crude curuculin, in particular, in the form of an aqueous solution, would have a poor stability upon storage since they are contaminated with proteases and bacteria contained in the Curculigo latifolia fruits. In addition, it is highly difficult to harvest a large amount of Curculigo latifolia fruits, since a Curculigo latifolia fruits, which has an ovoid figure with a process on the top, is as small as 1 cm in diameter and weighs only 1 g even in a fully ripened state. Thus it has been required to establish a method for efficiently obtain the taste-modifier comprising curculigo latifolia fruits, dried fruits thereof or a curucular-containing material obtained therefrom and to minimize the amount of the starting Curculigo latifoblia fruits in order to utilize said taste-modifier on a commercial scale.